Since getting back from holiday in the tropics three weeks ago, I have felt ill, hot and shivery. I went to the surgery and the nurse said it was flu. I didn't see the doc but he left me a prescription for antibiotics. However, they haven't made me any better. In fact, I feel dreadful. Any ideas?

Clearly, something is very wrong with you. Indeed, it sounds as if you may have malaria. You need urgent blood tests, including one called a blood film which detects malarial parasites. So please go to a doctor or a hospital today.